1. Field of the Invention
The present invention relates to freezers, and, more particularly, ice-making devices.
2. Description of the Related Art
The freezer portion of a refrigeration/freezer appliance often includes an ice cube maker which dispenses the ice cubes into a dispenser tray. A mold has a series of cavities, each of which is filled with water. The air surrounding the mold is cooled to a temperature below freezing so that each cavity forms an individual ice cube. As the water freezes, the ice cubes become bonded to the inner surfaces of the mold cavities.
In order to remove an ice cube from its mold cavity, it is first necessary to break the bond that forms during the freezing process between the ice cube and the inner surface of the mold cavity. In order to break the bond, it is known to heat the mold cavity, thereby melting the ice contacting the mold cavity on the outermost portion of the cube. The ice cube can then be scooped out or otherwise mechanically removed from the mold cavity and placed in the dispenser tray. A problem is that, since the mold cavity is heated and must be cooled down again, the time required to freeze the water is lengthened.
Another problem is that the heating of the mold increases the operational costs of the ice maker by consuming electrical power. Further, this heating must be offset with additional refrigeration in order to maintain a freezing ambient temperature, thereby consuming additional power. This is especially troublesome in view of government mandates which require freezers to increase their efficiency.
Yet another problem is that, since the mold cavity is heated, the water at the top, middle of the mold cavity freezes first and the freezing continues in outward directions. In this freezing process, the boundary between the ice and the water tends to push impurities to the outside of the cube. Thus, the impurities become highly visible on the outside of the cube and cause the cube to have an unappealing appearance. Also, the impurities tend to plate out or build up on the mold wall, thereby making ice cube removal more difficult.
A further problem is that vaporization of the water in the mold cavities causes frost to form on the walls of the freezer. More particularly, in a phenomenon termed "vapor flashing", vaporization occurs during the melting of the bond between the ice and the mold cavity. Moreover, vaporization adds to the latent load or the water removal load of the refrigerator.
Yet another problem is that the ice cube must be substantially completely frozen before it is capable of withstanding the stresses imparted by the melting and removal processes. This limits the throughput capacity of the ice maker.